Ron Guth: Beginning in 1965, all silver was removed from the Dime, Quarter Dollar, and Half Dollar denominations, in favor of a less expensive alloy consisting of outer layers of copper-nickel over a core of pure copper.
All dates and mintmark combinations are common in both Uncirculated and Proof conditions. However, a few mint errors add an extra challenge (and a lot of value) to the series: these are the no-mintmark Proof Dimes of 1968, 1970, 1975, and 1983). Other errors/varieties include the no mintmark Dimes of 1982, the Type 1 and Type 2 mintmarks of 1979 and 1981, plus the 1996W Dime (avaiable only in official U.S. Mint Sets). Coins in this series were produced at the Philadelphia, Denver, San Francisco, and West Point Mints.
This is the only denomination that has not undergone a major design change since 1965 (i.e. the 50 States Washington Quarter Dollars or the Bicentennial coins of 1976).